The ultimate goal is a "zero footprint" camp that would leave no waste behind and would reduce water and fuel coming in.

"We want to think inside the box, where the box is the base camp," said Patrick Taylor with Hughes Associates, a firm working with the Army Research, Development and Engineering Command on the concept.

The motivation is simple and increasingly urgent. The long logistics "tail" that follows troops into the war zone -- moving fuel, water and supplies in and waste out -- risks lives and diverts major resources from fighting, Department of Defense (DOD) officials say (ClimateWire, July 20).

Fuel and water represented two-thirds of the tonnage in Iraq convoys -- each one vulnerable to insurgents' explosives. Each must be protected by armored vehicles, helicopters and even fighter aircraft. Afghanistan's more remote, mountainous roads are still more challenging.

Slowly seeing this reality, the military has deployed simple measures first. The Army, for example, recently spent $95 million spraying tents in Iraq with foam insulation, slashing air conditioning demands nearly in half and eliminating an estimated 12 fuel convoys a day.

Now, DOD has $300 million from President Obama's economic stimulus to pursue energy research, supplementing funds it has already been devoting to that end. The hope is for longer-term solutions, some that could also one day make their way off the battlefield.

'Zero footprint' camp starts with garbage

That's where the garbage comes in. A good deal of the fuel used at forward operating bases goes toward powering electric generators. Meanwhile, every soldier produces an average of 7 pounds of waste daily. Taylor's firm estimates that a zero footprint camp could supply up to a third of its own fuel needs by reusing waste.

And while turning waste into electricity is not a new idea, doing it in small units in a harsh desert climate is another story.

Furthest along is the Tactical Garbage to Energy Refinery, which creates pellets from solid waste, then gasifies them to burn like propane. Liquids, meanwhile, are fermented into ethanol.

Able to process everything from plastic wrappers to food leftovers, two test units at Camp Victory in Iraq each powered 60-kilowatt generators until they broke down, said Taylor. Now they are back in the research shop being more ruggedly tuned.

The Defense Advanced Research Projects Agency (DARPA), the military's advanced research arm, is also developing a unit to produce 100 kilowatts, scheduled for a field test this year. And a contractor, IST Energy, developed the "Green Energy Machine," a unit it is now also marketing to commercial buildings.

Other DOD projects are looking to make water bottles from high-energy density plastics that would feed into these energy converters. Researchers are also working to redesign packaging to eliminate metals and other materials that can't be easily processed by them.

Some of these ideas have been in development for years but have languished in research stages. "There was no user saying, 'I need this, and this is how I need it to perform,'" said Taylor, speaking at a National Defense Industrial Association conference in May.

Army pushes to reduce the juice

That, however, is changing. The Army, for example, is now setting up renewable energy technology tests at some of its modular force provider camps. John Munroe, of the U.S. Army's Natick, Mass., Soldier Research, Development & Engineering Center, said that it will be looking for systems that are rugged and reliable and have a quick set-up.

With five C-17 cargo planes necessary to field one 550-man camp, he must also balance the benefits of renewable energy units against the added fuel burden of their transport. Cost, at least, is less of an issue.

"These things will pay for themselves very quickly," said Munroe.

"If the mission benefits are so strong, we don't have to justify the costs as much," said Taylor.

Garbage reuse is only one example. Small portable solar and wind systems are being tested for field use in the deserts of Fort Irwin, Calif., where soldiers simulate life in Iraq at the National Training Center, according to Barbara Brygider, who works with the Army's Power Surety Task Force.

There, they are also testing new tent structures, insulations and solar shades that could all lighten energy demand.

To connect and level the power from these various supplies, the Army is developing "microgrids," essentially central command systems to coordinate individual generators and distribute power more efficiently, according to Clark Borjack with Concurrent Technologies Corp., a nonprofit applied research and development firm.

Munroe estimates that demand monitoring on these grids might alone reduce consumption by a fifth.

Most importantly, perhaps, at Fort Irwin, they are gauging how much power and fuel a base actually needs. "We throw a lot of generators at the problem. But if you ask them how much they need, nobody knows," said Brygider.

She noted how important technology demonstration will be. "No commanding officer is going to let you take away a generator, unless you can prove it."

Wringing water out of air and fuel

Like fuel, water is also in high demand at military outposts. A deployed camp of 3,600 soldiers might need 25,000 gallons a day at the low end, all of which must be found, transported and purified in host countries, said Jay Dusenbury, deputy for science and technology with the U.S. Army TARDEC Force Projection Technology.

To better meet this demand, he said, the Army is working on low-energy desalination and small treatment systems to reuse shower water and even wastewater.

Early attempts to wring water from thin air and even from exhaust fumes are also intriguing. Systems that do both are being tested at Aberdeen Proving Ground, Md., said Dusenbury.

Making them worthwhile, however, will require more work. A demonstration unit can dehumidify ambient air and produce about 4 gallons of water per gallon of fuel, but that ratio would need to increase to make it worth the fuel it burns. The exhaust water system, which grabs and then purifies the water vapor produced as a normal combustion product, makes a gallon of water per gallon of fuel input.

While there may be plenty of alternatives to supply electricity, there are fewer for the diesel and jet fuel that power DOD's tactical vehicles, ships and aircraft. A full three-quarters of the military's total energy demand is jet fuel. Half of it is for aviation.

There are two ways DOD is approaching its fuel problem. One is to burn less. This, however, may be easy for a Toyota Prius but less so for a Navy destroyer.

The Navy floats a hybrid destroyer

That said, the Navy recently announced the awarding of a $33 million contract General Atomics to develop a hybrid electric drive system for its DDG 51 Class destroyers. "It's like putting a Prius engine on a destroyer," said Cotton. If successful, it could lower the ships' fuel consumption by 16 percent.

A second way to solve the fuel issue is by altering ship designs to reduce demand. This year, the Navy began installing stern flaps, an appendage to the bottom of a ship's hull that enables it to cut more smoothly through the water. The Navy estimates it can save up to $450,000 annually. The U.S. Coast Guard has already been using similar designs for its cutters, said Capt. John Hickey of the service's integrated support command center in Honolulu.

And as the Army designs its next generation of Humvees, it is looking at lighter, egg-crate-like prototypes designed to be protective like a cage, according to Alan Shaffer, DOD's principal deputy director for defense research and engineering.

Fuel consumption will be one of the factors it considers as it evaluates six to eight models for purchase within the next few years. Meanwhile, he said, the Air Force is testing high-efficiency advanced turbine engines and changing some of its flight training protocols.

Plans take off for an algae-based jet fuel

The Air Force, which burns about 2.5 billion gallons of jet fuel a year, will also trim that number as it relies more heavily on lighter-weight unmanned aerial vehicles, according to a Congressional Research Service report.

The even bigger question mark is whether DOD will be able to use alternatives to jet and diesel fuels. The Defense Energy Support Center, which runs the distribution of fuels from hundreds of supply points worldwide, is developing requirements for an alternative to JP-8 fuel, according to Donald Martin, an environmental protection specialist there.

To some, algae-based fuels might eventually become the best substitute. DARPA is funding research.

"Algae fuel has the potential to satisfy 100 percent of DOD's diesel and jet fuel needs and get buy-in from oil companies, because it is an alternative to petroleum -- not a replacement," said Michael Pacheco, vice president of deployment and industry partnerships at the National Renewable Energy Laboratory. He cautioned, however, that its commercial viability won't come for years.

Cotton said the Navy is looking to have a demonstration flight of an F-18 on a camelina-based fuel by the end of 2010.

In its search for a petroleum substitute, the Air Force has also spent years on work to make synthetic liquid fuels produced from a coal and natural gas a viable option, perhaps the nearest short-term option for it to meet a directive to acquire half of its domestic aviation fuel from alternative, domestic sources by 2016. Shaffer, however, called the coal-to-liquids option ultimately a "nonstarter," particularly because climate change is a looming issue.

In the end, its outsized reliance on liquid fuels is the biggest energy challenge for DOD.

"That's a different problem than America faces," said Shaffer. "At the end of the day, DOD has some unique problems, and we have to solve them."